The Pannonian Basin System northern margin paleogeography, climate, and depositional environments in the time range during MMCT (Central Paratethys, Novohrad-Nograd Basin, Slovakia)
Abstrakt
The Miocene global climatic changes together with profound regional tectonic activity significantly influenced the Central Paratethys epicontinental sea. The aim of this study was to reveal relationships between regional and global changes during the beginning Middle Miocene Climatic Transition.
The work focused on the northern margin of the Pannonian Basin System, on the key Burdigalian and Langhian sites from the Novohrad-Nograd and Danube basins (Slovakia). The outcrops and wells reveal variegated facial architecture, environments and processes.
The sedimentary record can be subdivided into four main stratigraphic intervals: (i) The late Burdigalian (Karpatian) NN4 Zone. (ii) The earliest Langhian (Karpatian? - earliest Badenian; 14.9 Ma and older), top of NN4/base NN5 Zone. (iii) The lower Langhian (lower Badenian) deposits of NN5 Zone estimated to be similar to 14.9-14.4 Ma old. (iv) The late Langhian (lower Badenian) sediments of NN5b-5c Zone with estimated age of 14.4 Ma or younger. Langhian (lower Badenian) rift related volcanism was responsible both for pronounced relief formation and for supply of nutrients and silica into the basin.
The Burdigalian/earliest Langhian shelf break slope mudstone (after hiatus) have been replaced by the Langhian inner to outer shelf environment dominated by tidal and wave processes. These were dominated by infaunal foraminifer associations which changed to epiphytic ones.
Occasionally the patchreef environment was recorded by miliolide forms. In general, on the southern edge of the Krupina volcanic field the shelf setting passed into deltaic and fluvial deposits.
Foraminiferal and calcareous nannoplankton assemblages point more to the nutrient decrease and circulation system change around the Bur/Lan boundary than to warm water condition, followed by cooling during the MMCT. Pollen spectra documents a slight post-Burdigalian cooling and aridification trend.